1. São Paulo State STD/AIDS Reference and Training Centre and NEPAIDS, São Paulo, Brazil
2. Casa da AIDS, São Paulo University Medical Centre, São Paulo, Brazil
3. Department of Social Psychology and NEPAIDS, University of São Paulo, São Paulo, Brazil
4. Department of Infectious Diseases, School of Medicine, University of São Paulo, São Paulo, Brazil
5. Department of Family and Community Medicine, University of California, San Francisco, USA